1 Field of the Invention
The present invention relates generally to methods of driving a flat display used as a thin display device, a wall-hung display device and the like and devices driving the same, and in particular to wirelessly connecting a display signal source and the flat display together and reducing the thickness, weight and cost of the flat display.
2. Description of the Background Art
A flat display used as a thin display device, a wall-hang display device or the like has been developed employing a thin film transistor (TFT), ferroelectric crystal liquid (FLCD), an STN liquid crystal display device, a plasma display or a combination of liquid crystal and a plasma display or PALC, electroluminescence (EL), a light emitting diode (LED) display, or the like, and it has also been increased in size and enhanced in definition year after year. The flat display is connected to a signal source, such as a personal computer, a TV set, Internet, a TV phone, a TV conference system. Wirelessly connecting the display signal source and the flat display has also been considered in order to alleviate the flat display""s circuit burden, weight and cost.
Table 1 represents a relationship between the flat display""s definition, clock frequency and displaying-color count.
It is apparent from Table 1 that with a panel resolution of VGA (640xc3x97480), 0.60 Gbps and 0.75 Gbps are required for 18- and 24-bit colors, respectively. To display a high-vision image with a resolution of 1920xc3x971080, 4.46 Gbps is required.
Japanese Patent Laying-Open No. 9-294271 discloses a technique of sending image data from a personal computer to a liquid crystal projector through infrared transmission and storing the image data in the liquid crystal projector. Japanese Utility Model Laying-Open No. 6-77086 also describes a technique of configuring a disc player and a liquid crystal display removably and communicating signals therebetween through a wire or wirelessly. The publications describing such techniques, however, do not fully describe any forms of transmitted and received signals, any configuration of a transmitter, any configuration of a receiver, or the like in detail.
Furthermore, while signal transmission rates of 0.75 Gbps and 4.46 Gbps are required for the VGA and high-vision panel resolutions, respectively, infrared only has a signal transmission rate of approximately at most 100 MBPS. This is a limitation in using infrared to wirelessly connect a flat display.
The present invention contemplates a method and device driving a flat display, capable of wirelessly coupling the flat display and a display signal source together.
Briefly speaking, the present invention provides a method of driving a flat display, including the steps of: upconverting a signal output from a display signal source to be displayed into a millimeter-wave and transmitting the millimeter-wave; receiving and downconverting the millimeter-wave to output the signal to be displayed; and supplying the signal to be displayed to the flat display.
The present invention, in another aspect, is a flat display drive device comprised of a display signal source, a first frequency converting circuit, a millimeter-wave transmission circuit, a millimeter-wave reception circuit, a second frequency conversion circuit, a signal separation circuit, a flat display, an x-direction driver, and a y-direction driver.
A display signal source generates a signal to be displayed. The first frequency converting circuit receives the signal to be displayed and converts it into a millimeter-wave. The millimeter-wave transmission circuit produces a radio-frequency (RF) wave for transmitting the millimeter-wave. The millimeter-wave reception circuit receives the radio-frequency wave to produce a millimeter-wave. Second frequency conversion circuit receives the millimeter-wave from the millimeter-wave reception circuit and converts it into the signal to be displayed. The signal separation circuit receives the signal to be displayed from the second frequency conversion circuit and separates it into an x-direction image signal and a y-direction image signal.
The flat display has a plurality of display elements arranged in a matrix, including an x-direction drive line arranged for each row of display elements and a y-direction chive line arranged for each column of display elements. The x-direction driver responds to the x-direction image signal by supplying to the x-direction drive line a voltage signal for driving a display element. The y-direction driver responds to the y-direction image signal by supplying to the y-direction drive line a voltage signal for driving a display element.
The present invention in still another aspect is a flat display drive device comprised of a display signal source, a signal separation circuit, a modulation circuit, a frequency converting circuit, a milliwave transmitter, a miniwave receiver, a demodulation circuit, a flat display, an x-direction driver, a y-direction driver, and first and second signal supply circuits.
The display signal source generates a signal to be displayed. The signal separation circuit separates the signal to be displayed into x- and y-direction signals for driving the flat display. The modulation circuit uses the x- and y-direction signals to modulate an intermediate frequency (IF) wave. The frequency converting circuit converts the IF wave modulated by the modulation circuit into a radio-frequency wave. The millimeter-wave transmitter generates a radio-frequency wave for transmitting a milimeter-wave. The millimeter-wave receiver receives the radio-frequency wave to produce a millimeter-wave. The demodulation circuit demodulates the millimeter-wave into x- and y-direction signals.
The flat display has a plurality of display elements arranged in rows and columns and also includes an x-direction drive line arranged for each row of display elements and a y-direction drive line arranged for each column of display elements. The x-direction driver supplies an x-direction signal to the x-direction drive line. The y-direction driver supplies a y-direction signal to the y-direction drive line. The first signal supply circuit supplies an x-direction signal to the x-direction driver. The second signal supply circuit supplies a y-direction signal to the y-direction driver.
The present invention in still another aspect is a flat display drive device comprised of a display signal source, a signal separation circuit, a modulation circuit, a millimeter-wave transmitter, a millimeter-wave receiver, a demodulation circuit, a flat display, an x-direction driver, a y-direction driver, and first and second signal supply circuits.
The display signal source generates a signal to be displayed. The signal separation circuit separates the signal to be displayed into x- and y-direction signals for driving the flat display. The modulation circuit modulates a millimeter-wave, depending on a signal obtained by time-division multiplexing the x- and y-direction signals. The millimeter-wave transmitter transmits via a radio-frequency wave a millimeter-wave corresponding to the milimeter-wave modulated by the modulation circuit, and the millimeter-wave transmitter incorporates a digital modulator therein.
The modulation circuit uses the x- and y-direction signals to modulate an intermediate-frequency (IF). The frequency converting circuit converts the IF wave modulated by the modulation circuit into a radio-frequency wave. The millimeter-wave transmitter generates a radio-frequency wave for transmitting a millimeter-wave. The millimeter-wave receiver receives the radio-frequency wave to produce a millimeter-wave. The demodulation circuit demodulates the millimeter-wave into x- and y-direction signals.
The flat display has a plurality of display elements arranged in rows and columns and also includes an x-direction drive line arranged for each row of display elements and a y-direction drive line arranged for each column of display elements.. The x-direction driver supplies an x-direction signal to the x-direction drive line. The y-direction driver supplies a y-direction signal to the y-direction chive line. The first signal supply circuit supplies an x-direction signal to the x-direction driver. The second signal supply circuit supplies a y-direction signal to the y-direction driver.
Thus a main advantage of the present invention is that since a display signal is transmitted and received in a millimeter-wave, ultra high-speed transmission of data greater in frequency than high-vision video signals can be achieved and the display signal""s bandwidth can be adequately covered to reduce transmission noise and modulation noise. Furthermore, since the display signal source and the flat display are coupled together wirelessly via a millimeter electric wave, the display signal source and the flat display can be arranged as desired to effectively enjoy the characteristics of the flat display, i.e., reduced thickness and weight.
Furthermore, millimeter-wave, harmless to the human body and also highly directional, allows the display signal source and the flat display to be readily matched in directionality. A millimeter-wave can also be damped significantly in the atmosphere, and it is thus advantageous in reduction of interference on other communication circuits and in reuse of a frequency space when it is used for relatively short distance communications, such as in a household, an office or the like.
Furthermore, since the transmitting side previously separates a signal to be displayed into x- and y-direction signals before it is transmitted, in the flat display the received x- and y-direction signals can be used to directly drive the x- and y-direction drive lines and a simple circuit configuration can thus be used to drive the display. Furthermore, in providing a 2-screen display, for example, the transmitting side is only required to transmit a signal to be displayed corresponding to a portion desired to be displayed and it is thus not necessary to transmit the data corresponding to the entire screen of the flat display, so that a transmission band can be used effectively.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.